Does working out at night hurt your sleep?

For most healthy adults, a workout in the evening doesn't make sleep any worse ¹. Exercising regularly helps people fall asleep a little faster and sleep a little longer, and they say they sleep better too ². So work out whenever you can fit it in, whether that's before work, on your lunch break or late in the evening once the house is quiet.

The one workout I'd move is a hard one that ends right before bed. When a hard workout ends within an hour of bed, people may take longer to fall asleep, sleep less and spend more of the night awake ¹. A hard workout that ends 2 to 4 hours before bed shouldn't disrupt your sleep, at least if you're a healthy young or middle-aged adult who usually sleeps well ³.

Working out late at night

Say the kids are down by 8:30 and you're on the bike in the garage or at the gym by 9. With an 11 o'clock bedtime, an hour-long workout ends at 10, exactly an hour before bed. That's right at the edge of where a hard workout can start to cost you sleep ¹. You don't have to give up the slot over that. Keep those late workouts at a pace where you can still talk, and save the hardest ones for a Saturday morning or any day you can go earlier. On the nights you can get going by 8:30, you're done by 9:30 and you've given yourself a bit more room.

Check the label on your pre-workout too, because a caffeinated scoop at 8:45 means you're having caffeine about two hours before bed. That's much later than you'd ever want your last coffee. On late nights, use one without caffeine or leave it out, and the same goes for the energy drink on the way there.

How to tell if a workout is hard

The easiest way to tell is the talk test. If you can talk but you couldn't sing, you're working at a moderate pace. If you can't say more than a few words without stopping for a breath, that's vigorous ⁴. In the studies, the only workouts that might have cost people sleep were vigorous ones that ended within an hour of bed ¹.

Running, swimming laps, fast cycling and kickboxing usually count as vigorous. Brisk walking, doubles tennis and power yoga are usually moderate. How fit you are changes it too, so a class that's moderate for the regulars can be vigorous for you if you're new to it ⁴. That's why your breathing that night is a better guide than the name of the class.

What to do after a late workout

Eat dinner before you go when you can, so you're not sitting down to a big meal at 10 at night. If you're hungry when you get back, keep it to something small. Once you're home, switching to lamps keeps the last hour before bed dim, even after a night under bright gym lights. After your shower, read for a while, and leave the work email for the morning so you're not lying in bed thinking about it.

Working out before work or at lunch

If you can fit a workout in before work, that's a bonus, because morning exercise can move your body clock earlier ⁵. A small study split 52 young adults who didn't usually exercise into a morning group and an evening group. After five mornings of workouts in a row, the morning group's body clocks had moved a little over half an hour earlier ⁵. The evening group, who trained around 6, barely moved on average ⁵. That average hid a split, though: the people whose body clocks ran later than the others seemed to move earlier, and the rest seemed to move later ⁵.

Some of the morning group's shift may have come from the daylight they got on the way to the lab ⁵. So when you do train in the morning, I'd do it outside or walk to the gym.

Most mornings there's no time for a real workout before work, and that's normal with a job and a family. A quick walk or some pushups still gets your body moving, and if you take the walk outside, you get some morning daylight as well.

A lunchtime workout is over hours before bed, and if you can take it outside, a run or a fast walk gets you daylight in the middle of a day you'd otherwise spend under office lights.

If a late workout keeps you up

If you're lying awake on the nights you train, I'd look at the pre-workout first. Go without the caffeine for a week or so, and if those nights don't get better, keep the late workouts easy.